BookMakes 96 pieces (2cm x 2cm) approx.
Line a swiss roll tin 9 x 13 inch (23 x 33cm) with parchment paper. Melt the butter on a low heat in a wide heavy bottomed saucepan. Stir in the evaporated milk, water and sugar. Bring to a gentle simmer. Cook on a very low heat, stirring constantly, until it reaches the soft ball stage, approx. 45 minutes.
To test, drop a teaspoon of the liquid fudge into cold water, it is ready when a smooth soft ball forms. Allow the fudge to cool in the pan for 3 minutes before whisking in vanilla. Immediately pour into the prepared tin and smooth the surface. Cut while still warm.
